Vascular endothelial cell glycoproteins are important in hemostasis and in the pathophysiology of the blood vessel wall. Endothelial cells and smooth muscle cells synthesize and secrete a variety of glycoproteins which a) function dynamically to modulate cell behavior at the sites of the vascular extracellular matrix, b) ensure hemostasis at the endothelial-blood interface and c) act after their release into the circulation. Therefore, we will study the synthesis and regulation of these important endothelial cell glycoproteins and correlate our studies with vascular tissue function. We will utilize established in vitro model systems including endothelial cell-coculture with smooth muscle cells and perfused intact vessels to examine how the modulation of the synthesis of specific glycoprotein products, their processing, and secretion may be regulated by both smooth muscle cell components and physiologically active agents, known to effect vascular functions. The majority the glycoproteins secreted by vascular endothelial cells in culture contain sulfated complex type ASN-linked oligosaccharide chains. Since most endothelial secretory glycoproteins are sulfated and since endothelial cells in culture incorporate 10-100 fold more 35SO4 into ASN-linked oligosaccharides of their secreted glycoproteins than smooth muscle cells, fibroblasts, or most tissues (exclusive of vascular beds), it is important to understand how sulfation of oligosaccharides is regulated and how sulfation fits into the general scheme of post-translational protein processing events. Because little is known of the cellular and molecular mechanisms that govern these processes, we will use both human vascular endothelial cells and murine haemangioendothelioma cells in culture to study the oligosaccharides and post-translational processing events of specific endothelial glycoproteins, identified by biochemical and immunological techniques. These studies will be correlated with studies testing the differential regulation of biosynthesis of glycoproteins secreted apically into the blood vs. into subendothelial compartments. We will test whether alterations in sulfation and oligosaccharide structure produced by oligosaccharide processing inhibitors effect protein processing, secretion and function. These studies will enhance our understanding of the regulation of endothelial function and the role of newly identified endothelial glycoproteins.